The invention relates generally to medical devices and more particularly to expandable medical devices and methods for treating vascular defects. For example, the invention can relate to expandable medical devices and methods for treating an aneurysm. Aneurysms are dilations in a blood vessel caused from weakening of a blood vessel wall. The dilation is produced by the pressure exerted by normal blood flow, which can cause the weakened segment of the blood vessel to swell. In some cases, this swelling results in a sac, or balloon-like polyp protruding from the main or parent vessel. Continued growth and/or eventual rupture of the ballooned arterial wall can have devastating results for a patient. As such, unruptured aneurysms should be treated to prevent hemorrhage. Additionally, ruptured aneurysms can be treated to avert a subsequent rupture and/or additional damage.
Some known medical devices and treatment methods used for treating an aneurysm include delivering a platinum coil to the sac of the aneurysm. The platinum coil is electrolytically separated from a delivery wire, thus inducing a charge in the coil which can cause a thrombotic effect in the aneurysm. In known procedures, about 30% of the volume of the aneurysm is packed with coils. Such known devices and methods, however, often have an about 30% recanalization rate, meaning blood flow returns to the aneurysm again and can cause the coil-packed aneurysm to swell further. Additionally, such known devices and methods require prolonged procedure times for the patient and correspondingly increased exposure to radiation for the patient. Moreover, such devices and methods do not treat the neck of the aneurysm, which is the area between the parent blood vessel and the sac of the aneurysm.
Another known treatment method includes the use of both a coil and a stent. The coil is delivered to the sac of the aneurysm as described above, and the stent is positioned within the parent blood vessel such that a portion of the stent is disposed over the neck of the aneurysm. Such procedures have several drawbacks. For one, delivery of two separate types of devices (i.e., coil(s) and a stent) is a more complex procedure, often resulting in a longer procedure time for the patient. The stent may lead to intra-stent stenosis of the blood vessel. Additionally, a patient would likely be required to take a blood thinner indefinitely following the procedure. Moreover, such devices and methods are not suitable for treatment of aneurysms positioned at a bifurcation of the blood vessel (i.e., between adjacent branches of a vessel).
Another known device and treatment method includes the use of a flow diverter delivered to the parent blood vessel adjacent the neck of the aneurysm. Generally, the flow diverter is positioned within the parent blood vessel over the neck of the aneurysm to prevent additional blood flow into the aneurysm from the vessel. In current procedures, more than one flow diverter is required per aneurysm to ensure blood flow is appropriately diverted from the aneurysm. Such a device and treatment method has similar drawbacks to the use of a stent, described above. Specifically, the flow diverter may lead to stenosis of the blood vessel and the patient would likely be required to take a blood thinner indefinitely following the procedure. Additionally, known flow diverters are not suitable for treating an aneurysm positioned at a bifurcation of the blood vessel. Moreover, long term follow-up of patients treated using a flow diverter is showing an increased rate of recanalization to the aneurysm.
Thus, there is a need for improved systems, devices and methods for treating vascular defects, such as balloon-type aneurysms, as described herein.